Alert archive / Iowa / Tornado Warnings in 2018

Tornado Warning 52, NWS Des Moines, IA

August 24, 2018Cerro Gordo County, Hancock County, Iowa

NWS Des Moines, IA issued this tornado warning at Aug 24, 2018, 6:33 PM CDT for Cerro Gordo County, Hancock County, Iowa. It was in force for 27 min. 5 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 24, 2018, 6:33 PM CDT (23:33 UTC)
Expired: Aug 24, 2018, 7:00 PM CDT
In force: 27 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 1.25 in

Counties Cerro Gordo County, IA, Hancock County, IA

The radar

The Des Moines radar (KDMX), 159 km from the middle of the area, began a volume at 23:35 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

Time	Report	Where	Remark
Aug 24, 6:43 PM CDT	HAIL 1	1 Wnw Clear Lake, IA	TRAINED SPOTTER REPORTED LOTS OF QUARTER SIZED HAIL.
Aug 24, 6:44 PM CDT	HAIL 1	1 Ne Clear Lake, IA	TRAINED SPOTTER REPORTED UP TO QUARTER SIZED HAIL.
Aug 24, 6:45 PM CDT	HAIL 1.25	3 Nw Clear Lake, IA	PUBLIC RELAYED A PICTURE OF HAIL LARGER THAN QUARTERS VIA TWITTER.
Aug 24, 6:50 PM CDT	HAIL 1.75	Clear Lake, IA	MEDIA RELAYED A PUBLIC SOCIAL MEDIA PICTURE OF LARGE HAIL, ESTIMATED AROUND GOLF BALL IN SIZE. TIME ESTIMATED FROM RADAR.
Aug 24, 6:56 PM CDT	HAIL 1.25	Clear Lake, IA	TRAINED SPOTTER REPORTED ONGOING QUARTER TO HALF DOLLAR SIZED HAIL.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 11.6 hours before the alert went out and 190 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 107 J/kg
Mixed-layer CIN: -122 J/kg
Mixed-layer LCL: 584 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 150 m²/s²
0-3 km storm-relative helicity: 149 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.6

Open this sounding in Storm Lab

The text

As transmitted.

365 
WFUS53 KDMX 242333
TORDMX
IAC033-081-250000-
/O.NEW.KDMX.TO.W.0052.180824T2333Z-180825T0000Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Des Moines IA
633 PM CDT FRI AUG 24 2018

The National Weather Service in Des Moines  has issued a

* Tornado Warning for...
  East central Hancock County in north central Iowa...
  Northwestern Cerro Gordo County in north central Iowa...

* Until 700 PM CDT.
    
* At 633 PM CDT, a severe thunderstorm capable of producing a tornado
  was located near Clear Lake, or 7 miles northeast of Garner, moving
  east at 25 mph.

  HAZARD...Tornado and half dollar size hail.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* This dangerous storm will be near...
  Clear Lake around 650 PM CDT.
  Mason City Municipal Airport around 655 PM CDT.
  Mason City around 700 PM CDT.

Other locations impacted by this tornadic thunderstorm include
McIntosh Woods State Park, Ventura and Clear Lake State Park.

This includes Interstate 35 between mile markers 188 and 197.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

This Tornado Warning replaces the Severe Thunderstorm Warning issued
for the same area.

To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Des Moines .

&&

LAT...LON 4315 9356 4321 9353 4318 9326 4303 9331
TIME...MOT...LOC 2333Z 291DEG 22KT 4317 9350 

TORNADO...RADAR INDICATED
HAIL...1.25IN

$$

Boksa

2 follow-up statements

997 
WWUS53 KDMX 242346
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
646 PM CDT FRI AUG 24 2018

IAC081-242355-
/O.CAN.KDMX.TO.W.0052.000000T0000Z-180825T0000Z/
Hancock IA-
646 PM CDT FRI AUG 24 2018

...THE TORNADO WARNING FOR EAST CENTRAL HANCOCK COUNTY IS
CANCELLED...
    
The tornadic thunderstorm which prompted the warning has moved out 
of the warned area. Therefore, the warning has been cancelled.

LAT...LON 4312 9349 4321 9349 4318 9326 4303 9331
TIME...MOT...LOC 2345Z 291DEG 22KT 4314 9340 

$$

IAC033-250000-
/O.CON.KDMX.TO.W.0052.000000T0000Z-180825T0000Z/
Cerro Gordo IA-
646 PM CDT FRI AUG 24 2018

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 700 PM CDT FOR
NORTHWESTERN CERRO GORDO COUNTY...
    
At 645 PM CDT, a severe thunderstorm capable of producing a tornado
was located over Clear Lake, or 10 miles west of Mason City, moving
east at 25 mph.

HAZARD...Tornado and half dollar size hail.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

This dangerous storm will be near...
  Mason City Municipal Airport around 655 PM CDT.
  Mason City around 700 PM CDT.

Other locations impacted by this tornadic thunderstorm include
McIntosh Woods State Park, Ventura and Clear Lake State Park.

This includes Interstate 35 between mile markers 188 and 197.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

If a tornado or other severe weather is spotted, report it to the
National Weather Service or your local nearest law enforcement agency
who will send your report. This act may save lives of others in the
path of dangerous weather.

&&

LAT...LON 4312 9349 4321 9349 4318 9326 4303 9331
TIME...MOT...LOC 2345Z 291DEG 22KT 4314 9340 

TORNADO...RADAR INDICATED
HAIL...1.25IN

$$

Boksa

406 
WWUS53 KDMX 250001
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
701 PM CDT FRI AUG 24 2018

IAC033-250010-
/O.EXP.KDMX.TO.W.0052.000000T0000Z-180825T0000Z/
Cerro Gordo IA-
701 PM CDT FRI AUG 24 2018

...THE TORNADO WARNING FOR NORTHWESTERN CERRO GORDO COUNTY HAS
EXPIRED...
    
The tornado threat has diminished and the Tornado Warning has been 
cancelled. However, large hail and damaging wind remains likely and 
a Severe Thunderstorm Warning remains in effect for the area.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
Des Moines .

Remember, a Severe Thunderstorm Warning still remains in effect for
Cerro Gordo County.

LAT...LON 4312 9349 4321 9349 4318 9326 4303 9331
TIME...MOT...LOC 0000Z 291DEG 22KT 4311 9328 

$$

Boksa

The office that day

Everything else NWS Des Moines, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 24, 8:38 AM CDT	Special Weather Statement	DMX	Crawford	52 min
Aug 24, 9:55 AM CDT	Special Weather Statement	DMX	Greene	35 min
Aug 24, 4:29 PM CDT	Special Weather Statement	DMX	Kossuth	61 min
Aug 24, 4:48 PM CDT	Severe Thunderstorm Warning	DMX	Kossuth, Winnebago	42 min
Aug 24, 5:20 PM CDT	Severe Thunderstorm Warning	DMX	Hancock, Kossuth, Winnebago	40 min
Aug 24, 6:11 PM CDT	Severe Thunderstorm Warning	DMX	Cerro Gordo, Hancock	49 min
Aug 24, 6:22 PM CDT	Special Weather Statement	DMX	Worth	53 min
Aug 24, 6:58 PM CDT	Severe Thunderstorm Warning	DMX	Cerro Gordo, Franklin	47 min

Nearby

Tornado Warnings in Iowa, 2018 Every tornado warning in 2018 Tornadoes in 2018

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.